The hydraulic control of a motor vehicle clutch is typically obtained by means of a hydraulic master cylinder which is in the general form of a jack, consisting essentially of a cylinder body within which a piston is mounted for axial sliding movement, the piston having a piston rod with a free end which projects axially out of the cylinder body.
In order to actuate the master cylinder, the driver will typically act on a clutch pedal which is articulated on to the bodywork of the vehicle. The clutch pedal is normally coupled to the free end of the piston rod of the master cylinder, the body of which is usually fixed on the bulkhead of the vehicle in front of the driver. Thus, when the driver presses on the clutch pedal, the variable volume chamber which is defined by the master cylinder body and the associated piston is pressurised.
In order to ensure smooth operation of the master cylinder, the latter (typically by means of the free end of the piston rod) must be articulated on the clutch pedal. For this purpose, it has previously been proposed to make use of a coupling device which comprises a ball joint, in which a ball is mounted for pivoting movement within a ball housing which carries a complementary thrust seating surface. The ball may be fixed either at the free end of the piston rod, or on the pedal, while the ball housing, or body of the fastening device, is fixed in opposed relationship with the ball, on the pedal or on the free end of the piston rod.
In addition, it is desirable that during assembly, the connection between the piston rod and the pedal should be made as easily as possible, and preferably by automated assembly means, that is to say without any need to make use of any fitting or fastening device such as a dowel, rivet, screw and so on.